1. Field of the Invention
The present invention pertains to a wireless apparatus and method for initiating (activating) communications of a datalink to remote devices without the use of any physically-connected or internal battery power within the remote objects. The invention is especially attractive for situations where it is desirable to activate communications with a remote device over an unlimited period of time without expending any internal energy reserves. The invention is particularly applicable to roving objects with no convenient continuous connection to an external power source (e.g. human beings and animals). It is also particularly useful for an armament system with a plurality of munitions which require pre-conditioning initialization prior to launch, but which have no direct wire umbilical connection to the host platform.
2. Description of the Related Art
Today""s data communications receiving systems generally require some form of externally- or internally (battery)- provided power to be utilized to initiate and/or maintain communications coming from a data transmitter. In some cases, that power is manually turned on and off by an operator. In other cases, a continuous source of power is provided by a wire connection to an external power source, or is obtained from an internal battery. In many cases, a wire connection is not feasible or desirable for reasons of continuous external power unavailability (e.g., roving objects such as human being,s or animals), or for reasons of cost. Use of an internal battery for continuous power suffers the disadvantage of limited link activation standby time caused by eventual exhaustion of the limited battery reserve, or the need for periodic battery recharging by such means as high-illumination photo-voltaic arrays.
One class of remote objects which requires a communications channel is that of precision guided munitions (PGM""s). Today""s PGM""s require varying degrees of prelaunch preparation, or initialization, to enable and prepare the PGM""s guidance system, and control targeting and launch sequencing. This is generally accomplished with a datalink between the host platform and the munitions, most commonly over a hardwire umbilical between the host platform and the PGM. A hardwire connection affords the ability to uniquely and individually communicate between the host platform and each object and to provide a source of power to sustain the communication process.
Recent innovations to reduce the cost of upgrading host platforms to interface with PGM""s have resulted in the elimination of the hardwire umbilical to PGM""s, using instead a wireless interface and self-contained munitions power. Current implementations of the wireless interface require that the munitions contain a standby power source, viz., a standby battery, to maintain a low-power operational mode of the receive data link as the munitions await for instructions to activate full datalink functionality. Such battery-powered implementations provide a relatively short (on the order of days) period of standby operation before the standby datalink battery needs to be replaced.
The prior art teaches methods to supply power for data link operation. Maisonneuve, et al. in U.S. Pat. No. 4,091,734, disclose employing fiber-optic connections to remotely located electrical apparatus to supply sufficient power for data link operation. Others might use large photo-voltaic optical (sunlight) power collection arrays, to supply sufficient power for data link operation.
U.S. Pat. No. 4,091,734, issued to Redmond, et al. teaches using power from a photo-voltaic cell stimulated by a visible light source to power an optical receiver datalink. Though Redmond""s teaching and implementation might be used for a light-activated control function, its range is limited to 20 inches, which is insufficient for remote (i.e., longer range) light activation control applications. Redmond, et al. teach the use of a direct IR carrier modulation which utilizes a modulation of the raw IR energy, i.e., 940 nanometers wavelength, for transmission of single information bits, then relying on a protocol to encode information, in Redmond""s case using a pulse numbers protocol. The Redmond, et al. approach can implement ranges only up to 20 inches (1.6 ft). This is not sufficient for some intended virtual umbilical applications (8 ft). It is the intent of the current invention to overcome such restrictive range limitations.
The modulation method employed by Redmond cannot, with any practical scaling or extension, meet many wireless range requirements. In particular, no practical xe2x80x9cscaled upxe2x80x9d version of Redmond""s techniques can feasibly achieve the required wireless range for dispersed munitions in an aircraft environment activation.
Redmond, et al. also teach a power conditioning, or accumulation, function. Redmond, et al., however, continuously applies this power to the power accumulator device (a capacitor) and data recovery circuit. This results in a requirement for a relatively high level of optical illumination to provide sufficient operating power.
To maximize the attractiveness of a wireless datalink to potential roving or stationary unpowered applications, there is clearly a need to remove the need for any power or data path physical connection to such remote devices in order to establish a communications link. Attractiveness is further enhanced by being able to extend the maintenance-free time of the datalink activation system employed and to achieve operation at lower levels of operating power.
It is therefore a principal object of the present invention to provide a datalink activation function of long duration for remote objects which have no physical connection to external power, this long duration being for the lifetime of the remote objects.
It is another object to be able to accomplish the activation function with a relatively low level of illumination at the receiving object(s) and with the use of relatively few light sources, which are remotely located from the object(s), to provide sufficient power to many objects at once, thereby permitting a practical implementation.
It is yet another object to maximize the installation cost benefits and low-maintenance attractiveness of a wireless interface data link to potential PGM customers by removing the need for any power or data path physical connection to remote devices to establish a communications link.
It is still another object to extend the maintenance-free time of the datalink activation system employed.
These and other objects are achieved by the wireless datalink activation system of the present invention. In its broad aspects, the system includes at least one data receiver, a low-power photo-voltaic power generation and distribution system, and a unique signal detector. The data receiver receives serial digital information from a remote optical data transmitter. The data receiver serves both activation and data/control wireless datalink functions. The low-power photo-voltaic power generation and distribution system includes at least one photo-voltaic panel for receiving optical power from a remote optical emission source; and power conditioning, accumulation, and distribution means. Such means includes a digital micro-power timer integrated circuit. The power conditioning, accumulation, and distribution means is connected to the photo-voltaic panel for accumulating power generated by the photo-voltaic panel for periodically and intermittently distributing accumulated power in desired quantities. The unique signal detector is connected to the data receiver and to the power conditioning, accumulation and distribution means, and is connectable to an electrical apparatus. The periodically and intermittently distributed power enables the unique signal detector to evaluate incoming data received from the data receiver, and upon detection of the receipt of a signal qualifying as a key, thereupon issues a command to the electrical apparatus to initiate uninterrupted data communication from the data receiver.
The system is capable of providing a lifetime physical-connection-free means of accomplishing remote datalink activation and subsequent communications functions to remote objects.
Its advantage is that only a low ambient lighting source is sufficient to provide the power necessary to initiate (activate) datalink functions with remote objects. The required power is accumulated. Only when a sufficient amount has been stored, then the stored power is switched to the data receiver. This technique of intermittent switched power application allows the use of a photo-voltaic power source which provides less than the amount of continuous power required for the data recovery function. This technique allows the power to be gathered over an extended period (e.g., 2 seconds), then applied over a relatively short period (e.g., 50 milliseconds). This affords a 40X improvement in available power for the data recovery circuitry, thereby permitting a proportionate reduction in the illumination intensity. Comparable reductions of illumination power and light intensity are possible with this innovation. The present invention affords the possibility of power accumulation and control function operation at more remote (longer) ranges than Redmond""s approach, making it applicable in many more potential applications.
This approach provides the very great advantage of allowing a remote object to remain in a standby mode indefinitely, without tapping internal battery energy storage reserves, until such time it is desired to initiate communications. This essentially preserves the entirety of a remote object""s internal battery storage capacity for the xe2x80x9cshelfxe2x80x9d lifetime of the battery.
In accordance with the principles of the present invention, a long-life or lifetime battery is permitted to be installed at the factory for devices which require communications functions, such remote identification modules and PGM weapons. This provides for the service life of the datalink activation system of up to that of the xe2x80x9cshelfxe2x80x9d life of the battery installed, typically on the order of 10 years for lithium batteries employed in objects such as smart munitions.